LSU President F. King Alexander reiterated that while the 18-year-old's death is being investigated as a "potential hazing incident," many details of what occurred before his death are still unknown.

All Greek activities at the university were suspended "indefinitely, pending the results of a thorough investigation," he said at a news conference.

"As we've continually warned over and over again, hazing is dangerous, irresponsible, and unacceptable, and it will not be tolerated at LSU period," Alexander said.

Read More

A preliminary autopsy found that Gruver had a "highly elevated blood alcohol level plus the presence of THC in the urine," said a statement released Friday by the East Baton Rouge Parish Coroner's Office.

THC is tetrahyrdrocannabibol, a chemical found in marijuana.

No cause of death was released. More detailed toxicology analysis is to come, so the autopsy could take four weeks longer to complete, the office said.

Fraternity members were interviewed, and no arrests have been made, said Ernie Ballard, the university's media relations director.

What officials know

A fellow fraternity member took Gruver to Our Lady of the Lake Regional Medical Center's emergency department Thursday, where he was pronounced dead shortly before noon, according to the coroner's office. Gruver was from Roswell, Georgia.

The fraternity contacted LSU's Greek Life office about 12:15 p.m. to inform them of an incident. That office then notified the university's police, which began investigating, Ballard said.

The Phi Delta Theta's LSU chapter has been suspended by LSU and by the fraternity's national office, which has also opened an investigation into the incident.

"We're committed to investigating this situation thoroughly. The chapter and any individuals who are found to have violated our policies will be held accountable," Bob Biggs, executive vice president and CEO of Phi Delta Theta General Headquarters, said in a press release.

The Phi Delta Theta house is owned by the fraternity's chapter, but it is considered on-campus housing by the university. A house mom lives in the fraternity house, Ballard told CNN. It is unknown whether the house mom was in the fraternity house the night before or on the morning of Gruver's death, he added.

"This is an evolving situation. We are investigating the matter with the utmost seriousness," Alexander said.

The fraternity did not have any registered or scheduled events with the school on September 13, the night before Gruver died, officials said.

LSU has a fall rush period where students can try to join a fraternity. The fall rush period has ended, and students who received invitations, or bids, to join fraternities are now in a pledging process to become a member.

Twenty-three percent of LSU's student body is in a Greek organization, according to Ballard.

"A young man's life was cut short last night, and we mourn the loss," the president said. "Our deepest sympathies and prayers go to his family and his friends."